Multilayered insole for footwear

ABSTRACT

A multilayered insole for footwear comprises a base layer having a first thickness, an intermediate layer having a second thickness and adhered to an upper surface of the base layer, and an upper layer having a third thickness and adhered to a free surface of the intermediate layer. The base and upper layers are both made of a first material formed by foamable polymeric resin compositions. The intermediate layer is made of a second material formed by foamable polymeric resin compositions mixed with recycled foamable polymeric materials. A sum of the first thickness of the base layer and the second thickness of said intermediate layer is larger than 0.5 mm. The third thickness of the upper layer can be from 2 mm to 5 mm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to insoles for footwear, and more particularly to a multilayered insole having good resistance to compression and excellent air permeability.

2. Description of the Related Art

U.S. Pat. No. 4,642,912 issued to Gray discloses an improved insole. The insole is characterized in that it consists of three layers. Each of the layers is constructed of flexible foam with a specific compressive strength. As a result, the retention rate of cushioning properties after wear of the insole is higher than that of prior art. But the drawback of the three-layer insole is that the air permeability thereof turns bad as comparing with prior art. In other words, the patented insoles may have good retention of cushioning properties after wear but the air permeability thereof is bad.

Thus, there exists a need for an insole having good retention of cushioning properties after wear as well as excellent air permeability.

Accordingly, the present invention provides a multilayered insole for footwear that has high retention rate of cushioning properties after wear as well as good air permeability.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a multilayered insole for footwear comprises a base layer having a first thickness, an intermediate layer having a second thickness and adhered to an upper surface of the base layer, and an upper layer having a third thickness and adhered to a free surface of the intermediate layer. The base and upper layers are both made of a first material formed by foamable polymeric resin compositions. The intermediate layer is made of a second material formed by foamable polymeric resin compositions mixed with recycled foamable polymeric materials. A sum of the first thickness of the base layer and the second thickness of said intermediate layer is larger than 0.5 mm. The third thickness of the upper layer can be from 2 mm to 5 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the insole according to the present invention will become more apparent hereinafter from the following detailed disclosure of a preferred, though not exclusive, embodiment of the invention, which is illustrated, by way of an indicative, but not limitative, example, in the accompanying drawings, where:

FIG. 1 is a perspective view of an insole according to an embodiment of the present invention;

FIG. 2 is a sectional view of the insole of FIG. 1 taken along section 2-2.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Referring to FIGS. 1 and 2, the insole 10 of the present invention generally comprises a base layer 12, an intermediate layer 14, an upper layer 16 and a top layer 20.

The base layer 12, which is made of a first foamable material formed by a foamable polyurethane resin, is preferably of generally flat construction with a thickness of 0.5 mm. The base layer 12, for having a thickness specially designed and being made of a foamable material not mixed with any other materials, has a better resistance to compression than any other foamable materials so as to provide a high retention rate of cushioning properties after wear.

The intermediate layer 14 is adhered to an upper surface of the base layer 12 and preferably is of generally flat construction. The intermediate layer 14 is made of a second foamable material formed by a foam polyurethane resin mixing with recycled polymeric foam materials. Such a foamable material, for being mixed with recycled polymeric foam materials, has a better air permeability than the first foamable material. For getting excellent air permeability and good resistance compression, the sum of the thickness of the base layer 12 and the thickness of the intermediate layer 14 is larger than 0.5 mm but smaller than 4 mm. In this embodiment, the thickness of the intermediate layer 14 is approximately 3 mm.

The upper layer 16 is also made of the first foamable material and adhered to an upper surface of the intermediate layer 14. The thickness of the upper layer 16 is preferably larger than the sum of the first thickness of the base layer 12 and the second thickness of the intermediate layer 14. In this embodiment, the thickness of the upper layer 16 is approximately 4 mm.

The top layer 20 is made of any suitable fabrics such as cloth. It is adhered to an upper surface of the upper layer 16 to increase the comfort and prevent sliding during wear.

As described above, we can clearly understand that the layers of the insole 10 are made of different foamable materials and each of them has a specific thickness. As a result, the retention rate of cushioning properties after wear and the air permeability of the insole 10 are both better than the prior art insoles. According to experiments made by the inventor, the retention rate of cushioning properties of the insole 10, when being worn six months, is 90%, but that of prior art insoles is less than 50%. The air permeability of the insole 10 is 500-700 l/m² see and that the prior art insoles is only 200-300 l/m² sec. 

1. A multilayered insole for footwear, comprising a base layer having a first thickness; an intermediate layer having a second thickness and adhered to an upper surface of said basic layer; and an upper layer having a third thickness and adhered to a free surface of an intermediate layer; said base and upper layers being made of a first foamable material formed by foamable polymeric resin compositions; said intermediate layer being made of a second foamable material formed by foamable polymeric resin compositions mixed with recycled foamable polymeric materials; a sum of said first thickness of said base layer and said second thickness of said intermediate layer being larger than 0.5 mm; and said third thickness of said upper layer being 2 mm to 5 mm.
 2. The insole of claim 1, wherein the sum of said first thickness of said base layer and said second thickness of said intermediate layer is larger than 0.5 mm but smaller than 4 mm.
 3. The insole of claim 1, wherein said first thickness of said base layer is smaller than said second thickness of said intermediate layer.
 4. The insole of claim 1, wherein said third thickness of said upper layer is larger than the sum of said first thickness of said base layer and said second thickness of said intermediate layer.
 5. The insole of claim 1, wherein said third thickness of said upper layer is 4 mm.
 6. The insole of claim 1, further comprising a top layer made of fabrics and adhered to a free surface of said upper layer. 